title: Magnetoencephalographic evidence for the modulation of cortical swallowing processing by transcranial direct current stimulation.
abstract: Swallowing is a complex neuromuscular task that is processed within multiple regions of the human brain. Rehabilitative treatment options for dysphagia due to neurological diseases are limited. Because the potential for adaptive cortical changes in compensation of disturbed swallowing is recognized, neuromodulation techniques like transcranial direct current stimulation (tDCS) are currently considered as a treatment option. Here we evaluate the effect of tDCS on cortical swallowing network activity and behavior. In a double-blind crossover study, anodal tDCS (20 min, 1 mA) or sham stimulation was administered over the left or right swallowing motor cortex in 21 healthy subjects in separate sessions. Cortical activation was measured using magnetoencephalography (MEG) before and after tDCS during cued "simple", "fast" and "challenged" swallow tasks with increasing levels of difficulty. Swallowing response times and accuracy were measured. Significant bilateral enhancement of cortical swallowing network activation was found in the theta frequency range after left tDCS in the fast swallow task (p=0.006) and following right tDCS in the challenged swallow task (p=0.007), but not after sham stimulation. No relevant behavioral effects were observed on swallow response time, but swallow precision improved after left tDCS (p<0.05). Anodal tDCS applied over the swallowing motor cortex of either hemisphere was able to increase bilateral swallow-related cortical network activation in a frequency specific manner. These neuroplastic effects were associated with subtle behavioral gains during complex swallow tasks in healthy individuals suggesting that tDCS deserves further evaluation as a treatment tool for dysphagia.
authors.affiliation: Institute for Biomagnetism and Biosignal Analysis, University of Muenster, Malmedyweg 15, 48149 Muenster, Germany; Department of Neurology, University of Muenster, Albert-Schweitzer-Campus 1, Gebäude A1, 48149 Münster, Germany. Electronic address: sonjasuntrup@uni-muenster.de.
authors.forename: Sonja
authors.initials: S
authors.lastname: Suntrup
authors.forename: Inga
authors.initials: I
authors.lastname: Teismann
authors.forename: Andreas
authors.initials: A
authors.lastname: Wollbrink
authors.forename: Martin
authors.initials: M
authors.lastname: Winkels
authors.forename: Tobias
authors.initials: T
authors.lastname: Warnecke
authors.forename: Agnes
authors.initials: A
authors.lastname: Flöel
authors.forename: Christo
authors.initials: C
authors.lastname: Pantev
authors.forename: Rainer
authors.initials: R
authors.lastname: Dziewas
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000465:Algorithms; D001931:Brain Mapping / Q000379:methods*; D018592:Cross-Over Studies; D003679:Deglutition / Q000502:physiology*; D004311:Double-Blind Method; D019317:Evidence-Based Medicine; D005260:Female; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D065908:Transcranial Direct Current Stimulation / Q000379:methods*
keywords: Deglutition; Magnetoencephalography; Neuroplasticity; Swallowing; Swallowing disorders; Transcranial direct current stimulation